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Wetland restoration project underway in eroded area of Ackerson Meadow

The National Park Service says a project to restore the 230 acre Ackerson Meadow area, recently added to Yosemite National Park, is the largest wetland restoration project in the park's history. Ninety acres of wetland habitat have been lost and 100 acres are at risk from a century-old erosion gully that has eroded more than 150,000 cubic yards of meadow soil.

Posted on August 23, 2023

A wetland restoration project is now underway in the 400-acre former herding area known as Ackerson Meadow, which was controversially added to Yosemite National Park in 2016, the National Park Service announced this week.

Ackerson Meadow is on the west edge of Yosemite, on Evergreen Road in Tuolumne County, between Highway 120 and the entrance to Hetch Hetchy, and it borders Stanislaus National Forest land. Ackerson Creek flows into the South Fork Tuolumne River.

Natural subalpine meadows there used to be magnets for cattle and sheep herders who sought grazelands when they were outside park boundaries. More than 150 years of grazing operations and landscape manipulation, including domestic water diversion, ranching, farming, fire suppression, and timber harvesting have changed the area, which is no longer wilderness.

A century-old erosion gully network, east of Evergreen Road, has consumed 90 acres of wetland habitat and put 100 more acres at risk, federal authorities say. The gully network has eroded more than 150,000 cubic yards — more than 15,000 10-yard dump-truck loads — of rich meadow soil.

The erosion gully network rapidly drains water from the meadows, dries soils, causes loss of water-loving plants and animals, and impacts endangered species, including birds like the great gray owl and little willow flycatcher, according to the park service.

The Ackerson Meadow area recently added to Yosemite National Park has changed over the past two centuries due to human land uses that include ranching, cattle grazing, fire suppression, ditching to drain the meadows, roads, fencing, and hunting.

Wildfires have burned in the area throughout history, and most recently the 2013 Rim Fire burned large patches of forested areas around Ackerson Meadow as well as within the meadows themselves, according to a 2021 Ackerson Meadow Restoration Environmental Assessment report.

The mixed-intensity Rim Fire left many standing dead trees. Some areas were logged and replanted on Forest Service and privately-owned lands around the Ackerson Meadow area. That did not happen on park service land. The meadows have “generally low levels of young conifer encroachment,” while Ackerson Meadow contains at least 10 ponderosa pines with diameters 30 inches or greater, and several incense cedars with diameters 18 inches or less.

This undated photo of a creek and erosion helps illustrate a May 2021 Ackerson Meadow Restoration Environmental Assessment report.

A partnership formed to restore Ackerson Meadow includes the U.S. Forest Service, the Stanislaus National Forest, Yosemite National Park, and the nonprofits Yosemite Conservancy and American Rivers.

The partners intend to restore and protect the Ackerson Meadow wetland by filling in the erosion gully network by fall 2024, and by planting more than 425,000 native wetland plants and 700 pounds of native seeds by spring 2025, according to the park service.

The acquisition of the Ackerson Meadow area by Yosemite National Park was criticized by local ranchers and held up as an example of further encroachment on the history of cattle and sheep herding that predates California statehood and the creation of Tuolumne County in 1850, as well as the later establishments of Yosemite National Park, the Stanislaus National Forest, the Forest Service, and the park service.

In December 2015, Shaun Crook was president of the Tuolumne County Farm Bureau and spoke against the park acquisition of the meadows at a county Board of Supervisors meeting.

“For over 100 years, the land has been managed through grazing and logging,” Crook said at the time. “Proper forest management has allowed the survival of the (great gray) owl and meadow. I strongly fear we will lose those qualities if it’s turned over to the national park.”

A 2021 report on historic properties in the meadow area says that in the past, Ackerson Meadow encompassed a large grazing operation that included private land holdings and grazing allotments in the Stanislaus National Forest. A ranch complex was present on a knoll east of Evergreen Road in a northern part of the meadow. Most of the ranch structures were removed before the federal land acquisition in 2016.

Remaining in the meadow at the time of the report were an abandoned wooden barn-garage built in the early 1950s, a network of dirt roads, multiple ditches, and abandoned split-rail, T-post, and barbed-wire fencing.

Before the addition of Ackerson Meadow to the park, it was privately-held land dating back to 1857, according to historians.

The nonprofit Trust for Public Land purchased Ackerson Meadow from private owners for $2.3 million in early 2016. The trust then donated the land to Yosemite Conservancy, American Rivers, and the park service.

Ackerson Meadow is one of the largest mid-elevation meadows in the Sierra Nevada, and the largest in Yosemite National Park, according to the park service. Goals of the meadow project include wetland function restoration, erosion reduction, and to:

• Protect existing intact wetlands from advancing gullies and headcuts, and re-establish hydrologic processes and conditions characterized by sheet flow and shallow dispersed swales.

• Restore the former extent of wetlands in Ackerson Meadow by reestablishing sustained high water tables: within 12 inches of the soil surface for 21 days per year.

• Minimize and mitigate impacts related to restoration actions.

• Restore natural habitat for at-risk wildlife species.

• Enable tribal participation in ecological restoration, tending, and gathering of traditional use plant materials.

• Provide continued grazing on US Forest Service-managed lands while protecting recovering wetlands, riparian areas, and archeological resources.

• Remove invasive plant species that threaten native species.

• Preserve wilderness character. In designated wilderness, minimize impacts to wilderness character by limiting restoration activities and tools to the minimum required to restore water tables and prevent further degradation.

The Central Sierra Environmental Resource Center in Twain Harte is among the nonprofits that have supported the restoration project.

“Ackerson Meadow is a truly iconic, special, and ecologically vibrant meadow system that is so severely degraded by a giant headcut, a gully that keeps working its way deeper into a meadow as erosion continues to take place, and so dried out in whole sections that once were ‘wet meadow’ that restoration is truly essential,” John Buckley, CSERC’s executive director, said Thursday in an email.

Buckley added that CSERC worked for years to get a large portion of the meadow transferred from private ownership to federal ownership.

Decades ago, bird surveys at Ackerson Meadow showed the area hosted one of the highest or the highest number of different visiting bird species of any major meadow in the Sierra Nevada, Buckley said.

Buckley said he walked the upper end of the meadow in spring 2022 under high runoff conditions.

“The key question for this giant restoration project is whether the design of the fill material being put into the gully can be done in a way that holds firmly despite huge gushing pulses of snowmelt or rain water flushing down into the meadow,” Buckley said Thursday.

Back in 2016, the owners of Ackerson Meadow who sold it to the Trust for Public Land, Robin and Nancy Wainwright, were contacted by the Associated Press. Robin Wainwright told the AP the couple also passed up a lucrative offer from a developer to build a resort on the land, and they lost a “few hundred thousand dollars” selling to the trust.

He also told the AP he often saw bears strolling through the meadow and owls soaring over fields of vibrant wildflowers blooming in the springtime. He said he didn’t want that experience available only to those who could afford a resort.

“To have that accessible by everyone to me is just a great thing,” Robin Wainwright said. “It was worth losing a little bit of money for that.”

The work underway at Ackerson Meadow is being billed by federal authorities as the largest wetland restoration project in Yosemite National Park history. For more information, go to


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